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目的研究血红素加氧酶-1系统(HO-1)对急性一氧化碳中毒大鼠脑海马损伤的保护作用及其机制。方法随机将90只大鼠分为4组,即空气对照组、急性一氧化碳(CO)染毒组、氯化高铁血红素(Hemin)+CO组、锡原卟啉(SnPP)+CO组,每组15~25只大鼠。采用Western blot法和免疫组化法测定HO-1蛋白的表达情况;测定各组大鼠脑水肿程度及大鼠24 h死亡率,脑海马丙二醛(MDA)浓度和caspase-3蛋白表达及活性水平变化;以HE染色观察脑海马神经元病理形态学改变及损伤程度。结果急性CO中毒组大鼠脑海马出现严重损伤,表现为染毒24 h后海马组织含水量为88.9%,死亡率为25%,海马MDA浓度4.23 nmol/mg,海马caspase-3活性(光密度值:4.67)和蛋白表达均显著升高,和空气对照组相比差异有统计学意义(P<0.01);病理学检测结果亦显示海马CA1区锥体细胞发生坏死,与对照组比较细胞密度降低44%。给予Hemin预处理能诱导大鼠海马HO-1高表达,并对海马损伤产生明显的保护作用,表现为Hemin预处理大鼠海马组织含水量降低,为84.2%;24 h死亡率降低为5%,海马MDA浓度为2.5 nmol/mg,caspase-3活性(光密度值:2.18)和蛋白表达明显低于CO染毒组。此外,Hemin预处理亦使染毒大鼠的病理学指标得到明显改善,海马CA1区锥体细胞坏死数目显著减少。HO活性抑制剂SnPP可部分阻断上述保护性作用,表现为SnPP预处理后CO染毒大鼠海马组织水肿程度加重(海马含水量为91.2%),24 h死亡率增加(30%),氧化损伤加重,海马CA1区锥体细胞出现明显水肿和坏死。结论HO-1诱导表达对急性CO中毒引起的大鼠脑海马损伤有明显的保护作用,提示HO-1系统在防护急性CO中毒海马损伤的病理过程中占有重要地位;HO-1的保护机制可能与其减轻脂质过氧化反应,抑制caspase-3蛋白表达和活性对抗细胞凋亡有关。
Objective To study the protective effect of heme oxygenase-1 system (HO-1) on hippocampal lesion in rats with acute carbon monoxide poisoning and its mechanism. Methods 90 rats were randomly divided into 4 groups: air control group, acute carbon monoxide (CO) group, Hemin + CO group, SnPP + CO group, Group 15 to 25 rats. Western blot and immunohistochemistry were used to detect the expression of HO-1 protein. Brain edema, 24 h mortality, MDA content and caspase-3 protein expression in hippocampus of rats were measured by Western blot and immunohistochemistry. The changes of the pathological changes and the degree of injury of hippocampal neurons were observed by HE staining. Results Severe injury of hippocampus was observed in acute CO poisoning rats. The 24 h after exposure, the water content of hippocampus was 88.9%, the mortality rate was 25%, the MDA content in hippocampus was 4.23 nmol / mg, the activity of caspase-3 in hippocampus (P <0.01). The results of pathology also showed that the pyramidal neurons in hippocampal CA1 area were necrotic, compared with the control group, the cell density Reduce by 44%. Hemin preconditioning could induce hippocampal HO-1 overexpression in rat hippocampus and significantly reduce hippocampal damage. Hemin preconditioning decreased the water content of hippocampus in rats by 84.2% and decreased the mortality rate to 5% at 24 h , The MDA content in hippocampus was 2.5 nmol / mg, the activity of caspase-3 (optical density value: 2.18) and protein expression were significantly lower than those in CO-treated group. In addition, pretreatment with Hemin also significantly improved the pathological parameters of the exposed rats, and significantly reduced the number of pyramidal neurons in the hippocampal CA1 region. HOPP inhibitor SnPP partially blocked the above protective effect, which was manifested as the increase of hippocampal edema (91.2% in hippocampus), the increase of 24 h mortality (30%), oxidation Increased injury, hippocampal CA1 pyramidal cells showed significant edema and necrosis. Conclusions HO-1 induced significant protective effect on hippocampal damage induced by acute CO poisoning, suggesting that HO-1 system plays an important role in the pathological process of protecting hippocampus from acute CO poisoning. The protective mechanism of HO-1 may be With its reduction of lipid peroxidation, inhibition of caspase-3 protein expression and activity of anti-apoptosis.